Method for Producing an Integrated Circuit Pointed Element, and Corresponding Integrated Circuit

ABSTRACT

A method for producing an integrated circuit pointed element is disclosed. An element has a projection with a concave part directing its concavity towards the element. The element includes a first etchable material. A zone is formed around the concave part of the element. The zone includes a second material that is less rapidly etchable than the first material for a particular etchant. The first material and the second material are etched with the particular etchant to form an open crater in the concave part and thus to form a pointed region of the element.

This application claims priority to French Patent Application 1260912,which was filed Nov. 16, 2012 and is incorporated herein by reference.

TECHNICAL FIELD

The invention relates to integrated circuits and, in particularembodiments, to the formation of tips in and/or on an integratedcircuit.

BACKGROUND

The tip effect is used in certain devices, especially to increase thefield effect.

Thus, it is known, in charge-storage nonvolatile memories, to createtips on the polysilicon floating gate, so as to facilitate the injectionof carriers into the upper gate.

It is possible in this regard to cite U.S. Pat. Nos. 5,783,473,6,410,957 and 6,635,922 as well as the following articles:

“An Analytical Model for Optimization of Programming Efficiency andUniformity of Split Gate Source-Side Injection Superflash Memory”,Huinan Guan, IEEE Transactions on Electron Devices, vol. 50, No. 3,March 2003,

“A Novel 3 Volts-Only, Small Sector Erase, High Density Flash EPROM”,Sohrab Kianian et al., 1994 Symposium on VLSI Technology Digest ofTechnical Papers, 1994 IEEE,

“Tunneling Phenomenon in Superflash® Cell”, A. Kotov et al., 2002 IEEENonvolatile Memory Technology Symposium, p. 110-115.

The formation of the tips of the floating gate comprises an oxidation ofthe polysilicon of this floating gate.

SUMMARY

The conventional method is limited to the fabrication of tips on apolysilicon region in the part of the integrated circuit customarilydesignated by the person skilled in the art under the acronym “FEOL”(Front End Of Line) and requires a significant thermal budget.

According to one mode of implementation, it is proposed to produce tipsin an integrated circuit, both in the FEOL part and in theinterconnection part situated above this FEOL part and commonlydesignated by the person skilled in the art under the acronym “BEOL”(Back End Of Line), while preserving substantially the same thermalbudget as that used customarily for producing an integrated circuit, andwithout being limited to polysilicon.

According to one aspect, a method for producing an integrated circuitpointed element comprises formation of an element possessing at leastone projection having a concave part directing its concavity towards theelement and comprising a first etchable material. The material can be,for example, polysilicon or a metallic material such as aluminum. Aformation around the concave part of a zone comprises a second materialless rapidly etchable than the first material, for example a materialused in the so-called “BARC” (Bottom Anti Reflective Coating)anti-reflection layers, or else a resin or indeed a carbonaceous layer.

The method also comprises an etching of the first material and of thesecond material so as to form an open crater in the concave part andthus to form a pointed region of the element.

Thus, according to this aspect, the formation of tips is obtained simplyby etching two materials at the level of a concave projection, and, theselectivity of etching as well as the duration of etching make itpossible to adjust the depth and the width of the crater, thereby makingit possible to adjust the height of the tips as well as the opening ofthe pointed region. The use of etching(s) makes it possible to avoid asignificant thermal budget for the formation of these tips.

Moreover, these production steps can be performed at any site of theintegrated circuit, be it in the FEOL part or in the BEOL part, and withany materials, provided that the materials used are etchable.

According to one mode of implementation, the formation of the zonecomprising the second material, comprises a formation of a layer of thesecond material above and around the at least one concave part, and aremoval, for example by a mechanochemical polishing, of a part of thislayer so as to abrade the crown of this concave part, and the formationof the crater then comprises the simultaneous etching of the firstmaterial and of the second material.

It is also possible, after the etching of the first material and of thesecond material, to remove the second material, so as to release theexterior of the pointed region.

Preferably, the element and the at least one projection comprise thesame first material. Stated otherwise, the element and its projection orprojections are formed of one and the same material.

In this case, according to one mode of implementation, the formation ofthe element comprises a formation of a support, made for example ofsilicon or else silicon oxide, comprising at least one salient block anda compliant deposition of a layer of the first material on the support,the part of the layer overlapping the at least one block forming the atleast one projection.

In this case, the projection can take the form of a dome, autoaligned onthe subjacent salient block.

According to one mode of implementation, it is possible to form anelement possessing several projections and to form the zone comprisingthe second material around each concave part and between two adjacentconcave parts. An etching of the first material and of the secondmaterial is then undertaken so as to form an open crater in each concavepart, and thus to form several pointed regions.

The formation of the element can comprise a formation of a supportcomprising several salient blocks and a compliant deposition of a layerof the first material on the support, the part of the layer overlappingthe blocks forming the projections.

According to another aspect, a device comprises at least one element ofan integrated circuit having at least one projection, comprising in itsupper part a pointed region limiting an open crater whose opening issmaller than the distance, reckoned at the level of the bottom of thecrater, between two points of the external wall of the pointed regionthat are substantially opposite with respect to the center of thecrater. Stated otherwise, the pointed region broadens out in thedirection of its base the further one recedes from the center of thecrater.

According to one embodiment, the external wall of the pointed regionexhibits a concave profile extending from the opening of the crater anddirecting its concavity towards the crater.

The crater can exhibit a hollowed part at the foot of the internal wallof the pointed region.

According to one embodiment, the device furthermore comprises a supportpossessing at least one salient block, and the element is then situatedabove the support with the pointed region autoaligned with the block.

According to one embodiment, the at least one projection and theremainder of the at least one element comprise one and the same firstmaterial.

The at least one element can comprise several projections, eachpossessing a pointed region.

According to another aspect, there is proposed an integrated circuitcomprising at least one device such as defined hereinabove.

The integrated circuit can comprise for example at least one capacitor,at least one electrode of which is formed by the at least one pointedelement of the device.

According to one embodiment, the at least one element of the device ismetallic and is situated on at least one of the metallization levels ofthe interconnection part (BEOL) of the integrated circuit.

The use of pointed elements, in particular metallic, in an integratedcircuit can find numerous applications.

Thus, in addition to an application to a capacitor, a pointed elementsuch as this can be used to release a beam of a mechanical system forelectrical switching or else to reduce the contact area, and thereforethe risk of sticking, of a body moving on a plane wall, such as forexample in a system for detecting orientation of the integrated circuit.

More precisely, according to one embodiment, the integrated circuitcomprises, within the interconnection part (BEOL), a mechanical systemfor electrical switching comprising in a housing at least one firstthermally deformable assembly including a beam held in at least twodifferent places by at least two arms secured to edges of the housing.The beam and the arms are metallic and situated within one and the samefirst metallization level. The system also comprises an electricallyconducting body. The first assembly has at least one first configurationwhen it has a first temperature and a second configuration when at leastone of the arms has a second temperature different from the firsttemperature. The beam is remote from the body in one of theconfigurations and in contact with the body and immobilized by the bodyin the other configuration so as to be able to establish or prohibit anelectrical link passing through the body and through the beam. The firstassembly is activatable to pass from one of the configurations toanother. The mechanical system furthermore comprises a release mechanismconfigured to release a beam immobilized by the body and comprising theat least one pointed element whose at least one pointed region isdirected towards the body, as well as a way to generate at the level ofthe at least one pointed region an electrostatic field.

According to another embodiment, the integrated circuit can comprise,within the interconnection part, at least one mechanical system fordetecting spatial orientation and/or change of orientation of theintegrated circuit. This mechanical system comprises a housing whosewalls comprise metallic portions produced within various metallizationlevels. The housing comprises a floor wall and a ceiling wall. Thedetection system also comprises a metallic piece housed in the housingand mobile inside the housing. A check mechanism is defines an evolutionzone inside the housing for the metallic piece and comprises at leasttwo electrically conducting elements disposed at the boundary of theevolution zone. At least one of the floor and ceiling walls incorporatesthe at least one element directing its pointed region towards themetallic piece inside the evolution zone. The piece is configured so as,under the action of gravity, to come into contact with the at least twoelectrically conducting elements, in response to at least one givenspatial orientation of the integrated circuit. The system also comprisesa detector to detect an electrical link passing through the piece andthe at least two electrically conducting elements.

BRIEF DESCRIPTION OF THE DRAWINGS

Other advantages and characteristics of the invention will be apparenton examining the detailed description of wholly non-limiting modes ofimplementation and embodiments, and the appended drawings in which:

FIGS. 1 to 11 illustrate various modes of implementation and embodimentsof a device and of an integrated circuit according to the invention,

FIGS. 12 to 17 illustrate another embodiment of an integrated circuitaccording to the invention, and

FIGS. 18 and 19 illustrate another embodiment of an integrated circuitaccording to the invention.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

In FIG. 1, the reference SP designates a support or substrate, (forexample silicon, polysilicon, silicon oxide, etc.).

As will now be seen in greater detail, a pattern comprising hollows andsalient blocks (or bumps) will be produced in this support.

In this regard, as illustrated in FIG. 1, the location of the hollows ofthe pattern is defined in a conventional manner by a photolithographystep using a photosensitive resin A.

Next, an etching of the support SP is undertaken in a conventionalmanner between the resin pads so as to form the hollows CRX of thepattern (FIG. 2).

After removal of the resin blocks, the support SP is obtained. Asillustrated in FIG. 3, the support SP comprises salient blocks BLCseparated by hollows CRX.

Next, as illustrated in FIG. 4, a layer CH1 of a first material B isformed on the support SP. The layer CH1 comprises projections formedabove and autoaligned with the subjacent salient blocks BLC. In thisexample, the projections are in the form of domes DM.

This layer CH1 therefore forms an element ELM resting on the support SPand comprising several projections DM.

This element ELM and its projections DM are formed of a first etchablematerial B which may be for example silicon, polysilicon, silicondioxide, silicon nitride, or else a metal such as aluminum or tungsten,without this list being exhaustive.

By way of indication, when the first metal forming the layer CH1 isaluminum, the deposition of this metal can be a Physical VaporDeposition (termed “PVD deposition”). When the first material is anoxide, it is then possible to use a Chemical Vapor Deposition (termed“CVD deposition”).

Such depositions are conventional and known per se.

In the following step, illustrated in FIG. 5, a layer CH2 of a secondmaterial C is formed on the structure obtained in FIG. 4. The secondmaterial C is also etchable and in this example possesses a planar uppersurface. This formation can be performed in various ways, for example bydepositing a planarizing material or else by performing a compliantdeposition of this material C followed by a mechanochemical polishing.

By way of nonlimiting example, it is possible to use as planarizingmaterial a material used in the so-called BARC anti-reflection layers.Thus, it is possible to use, for example, a material of the typeSiO_(x)N_(y). When oxide is used as material C, it is possible todeposit it by a so-called HDP (High Density Plasma) method or else toperform a compliant oxide deposition followed by a mechanochemicalpolishing.

Be that as it may, the second material C should be able to be etchedless rapidly than the first material B.

Indeed, it is this difference in etching speed or this selectivity ofetching, that will allow the creation of a pointed region in each domeDM.

More precisely, on the basis of the structure illustrated in FIG. 5, aremoval of the upper part of the layer CH2 is undertaken, so as toabrade the crown of each concave part, as illustrated in FIG. 6. At thisjuncture, around each concave part DM and between two adjacent concaveparts is a zone Z1 filled with the second material C.

Next, as illustrated in FIG. 7, a selective, isotropic or anisotropic,etching GRV of the material B and of the material C is undertaken so asto open in each concave projection DM, a crater CRT.

By way of indication, the selectivity of the etching can be of the orderof 1 for 2 or of 1 for 4.

Thus, for example, when the first material B is polysilicon and thesecond material C is a material of BARC type, it is possible to useplasma etching using a ClHBrO₂ plasma. This etching is typicallyperformed at 60° C. and the selectivity is then of the order of ½.

When the first material B is aluminum, and the second material C is alsoa material of BARC type, a BCl₃ArO₂ plasma can be used as plasma for theetching. This time the etching is performed at 40° C. and here again theselectivity is of the order of ½.

It should be noted that to pass from the structure of FIG. 5 to that ofFIG. 6, that is to say to remove the upper part of the layer CH₂ of thesecond material C, it is possible either to use specific etching andthen to use selective etching when in the situation of FIG. 6, or elseto use right from the outset the etching which will be used toselectively remove the materials B and C.

When the structure is in the state illustrated in FIG. 6, the selectiveetching GRV hollows out the first material B more deeply than the secondmaterial C, creating at the start a narrow crater. Next, as the materialC of each zone Z1 is etched, an additional part of the dome DM isuncovered, and then etched by the etching GRV. Thus, in tandem with theetching operation GRV, the crater CRT is hollowed out and widened. Thedimensions of the crater therefore depend on the selectivity of etchingand the duration of etching.

On completion of the etching operation GRV, the structure illustrated inFIG. 7 is obtained, in which the pointed element ELM comprises the lowerpart of the layer CH1, crenellated, as well as concave projections DMcomprising, in their upper part, a pointed region RGP whose internalwall PIT limits a crater CRT. Moreover, the opening OV of the crater issmaller than the distance d, reckoned at the level of the bottom of thecrater, between two points of the external wall PXT of the pointedregion which are substantially opposite with respect to the center ofthe crater.

The pointed region RGP broadens out therefore from the pointed endtowards the base the further one recedes from the center of the crater.

The external wall PXT of the pointed region exhibits here a concaveprofile extending from the opening OV of the crater while directing itsconcavity towards the crater.

Moreover, the pointed region RGP is autoaligned with the subjacentsalient block BLC of the support SP, that is to say the axis of symmetryof the block BCL coincides exactly or nearly with the axis of symmetryof the pointed region RGP.

In general, it is possible thereafter to undertake total removal of thematerial C situated in the zones Z2 between the pointed regions. Thiscan be performed by a totally selective etching aimed this time atetching the material C without etching the material B.

It is also possible in certain applications, as will be seen in greaterdetail hereinafter, to also remove by a selective etching operation, thesupport SP supporting the element ELM so as for example to form ametallic beam in the BEOL part of an integrated circuit.

In FIG. 8, the support SP comprises active zones ZA, of silicon orpolysilicon, mutually separated by isolating regions RIS, for example ofthe shallow trench type (STI: Shallow Trench Isolation). Each activezone is surmounted by a gate oxide OX. The isolating regions RIS havebeen slightly etched in such a way that the active regions ZA surmountedby the gate oxides OX form the salient blocks leading to the formationof the domes of the layer CH1 of the first material.

The layer CH1 is surmounted by the layer CH2. In the example describedhere, the layer CH1 can be polysilicon while the layer CH2 is here againfor example a material of BARC type.

In a manner analogous to what was described hereinabove, the etchings ofthe materials of the layers CH1 and CH2 are undertaken so as to form inthe layer CH1 pointed regions RGP delimiting craters CRT, the pointedregions RGP being autoaligned with the subjacent active zones.

It will thus be possible, after subsequent etching treatments, todelimit gates equipped with tips. As a variant, these etching treatmentsmaking it possible to delimit the gates can be performed before theformation of the tips.

It is seen in FIG. 10 that the etching of the zones RIS has caused ahollowed profile CRP between the edge of the active zone ZA and the edgeof the isolating region RIS. Therefore, on account of the compliantdeposition of the layer CH1 and the selective etching, the crater CRTexhibits a hollowed part CR1 at the foot of the internal wall of thepointed region.

By way of indication, the method makes it possible to obtain heights oftips of from 300 to 400 Ängstroms without this range of values beinglimiting.

It is possible, as illustrated in FIG. 11, to produce within anintegrated circuit a capacitor CDS. At least one of whose electrodes,here the lower electrode, comprises a pointed element.

More precisely, in this example, the pointed element ELM comprises asubstrate SP, of for example silicon dioxide, surmounted by the firstlayer CH1, of for example polysilicon, comprising several pointedregions and forming the lower electrode of the capacitor CDS. Adielectric layer CH3 is thereafter deposited on the layer CH1 and thesecond electrode CH4 of the capacitor, for example also of polysilicon,is thereafter deposited on the dielectric layer CH3.

A capacitor having an increased inter-electrode area relative to acapacitor whose two electrodes are plane is therefore obtained. And, forequal capacitive value, it is therefore possible to reduce the surfacearea of the capacitor on the silicon, for example of the order ofseveral tens of percent.

Reference is now made more particularly to FIGS. 12 to 17 to illustratean application of a pointed element to a mechanical switching systemdisposed in the interconnection part PITX (or BEOL) of an integratedcircuit.

An exemplary mechanical switching system is described in French patentapplication No. 1161410.

Certain characteristics thereof are now recalled hereinafter.

Referring to FIG. 12, which includes FIGS. 12A and 12B, it is seen thatthe mechanical switching system or switch CMT here comprises a firstassembly ENS1 produced within one and the same metallization level Mi ofthe interconnection part PITX of the integrated circuit CI.

This part PITX is situated above the substrate SB.

The switch CMT is in this example metallic, for example aluminum.

The switch CMT here comprises an assembly ENS1 in the form of anasymmetric cross. This assembly ENS1 comprises a first arm BR1A and asecond arm BR1B secured to a beam PTR, also dubbed the “centralpointer”, at two locations EMPA and EMPB respectively situated on twoopposite faces of the beam PTR. These two locations EMPA and EMPB arespaced a distance d apart.

FIG. 12A shows the switch CMT, and more particularly the assembly ENS1encapsulated in an isolating region RIS while FIG. 12B shows the sameassembly after etching of the isolating region so as to release the armsBR1A and BR1B as well as the beam PTR.

The assembly ENS1, thus released, therefore extends inside a housing LGresulting from the removal of the isolating region RIS, the two armsBR1A and BR1B being secured to the edges BDA and BDB of the housing.

It was shown in the article by R. Vayrette et al. entitled: “Residualstress estimation in damascene copper interconnects using embeddedsensors”, Microelectronics Engineering 87 (2010) 412-415, that afterde-encapsulation of an assembly of this type, there is stressrelaxation, which causes a residual longitudinal deformation of the armscausing a deviation a of the pointer, here clockwise.

More precisely, assuming an arm of constant width Wa, the deviation a isexpressed by the following formula:

$a = \frac{d \cdot L \cdot {L_{0}\left( {L - L_{0}} \right)}}{{d^{2}\left( {{2L} - L_{0}} \right)} + {\frac{4}{3} \cdot W_{a}^{2} \cdot L_{0}}}$

where L₀ is the length of the arm after relaxation,

L₀ is equal to

$\frac{L}{{1 + \frac{\sigma}{E}}\;}$

where σ designates the residual mean longitudinal stress and E theYoung's modulus of the material.

σ is determined experimentally on the basis of measurements performed ontest structures exhibiting various values of d and various values of Wa.

According to the applications which will be envisaged, and especiallyaccording to the precision desired, for example in the case oftemperature detection, it will be possible to take account or not takeaccount of this residual deviation a of the pointer PTR.

In this regard, and in a general manner, knowing the thermal expansioncoefficient of the material forming the expansion arms, the geometry ofthe arms, especially their length and their width as well as theirthickness, and the spacing d between the two fixing points, it isreadily possible to simulate, especially by calculations of moments offorces, the deviation of the pointer PTR during a temperature rise or atemperature fall.

In the embodiment illustrated in FIG. 13 and FIG. 14, the arms BR1A andBR1B of the assembly ENS1 are fixed in the vicinity of a first end zoneof the beam PTR, the other end zone ZXT of this beam PTR being free. Theswitch CMT moreover comprises an electrically conducting body CPS herecomprising a cantilever beam PTL secured to a part BDC of an edge of thehousing LG, as well as a metallic appendage VX situated at the free endof the beam PTL.

As seen more particularly in FIG. 14, the beam PTR (as well as the armsBR1A and BR1B of the assembly ENS1) is produced within a firstmetallization level, namely here the metallization level N while thecantilever beam PTL of the body CTS is produced within anothermetallization level different from the first metallization level, inthis instance the metallization level N+1.

Moreover, the appendage VX of the body CPS is produced within the levelof vias, situated between the metallization levels N and N+1. Theappendage VX is produced in a manner analogous to that used forproducing the vias in the BEOL part of the integrated circuit. Thatsaid, the appendage VX comprises a part VXA extending between the twometallization levels N and N+1, and prolonged by an end part VXBextending in part within the first metallization level N. This end partVXB broadens out towards the cantilever beam PTL.

In FIG. 13, the assembly ENS1 is in a first configuration, for examplewhen it is at ambient temperature. During a rise in temperature of theintegrated circuit, and consequently of the assembly ENS1, the arms BR1Aand BR1B of the assembly expand and therefore, the end ZXT of the beamPTR undergoes a motion MVT1 that is manifested here by a sagging.Moreover, the cantilever beam PTL of the body CPS expands and its freeend, supporting the appendage VX, moves according to a motion MVT2.

Therefore, and having regard to the fact that the amplitude of thesemotions can readily be calculated as indicated hereinabove as a functionespecially of the geometry of the arms and of the coefficients ofexpansion of the materials, the spacing ED between the end ZXT of thebeam PTR and the via VX, in the first configuration, is determined insuch a way that beyond a certain temperature, the assembly ENS1 takes asecond configuration in which, as illustrated in FIG. 14, the end zoneZXT of the beam PTR comes from the other side of the via VX, thus beingimmobilized and hooked by the via VX of the body CPS.

Passage of the end zone ZXT of the beam PTR from one side to the otherof the via VX is rendered possible especially by the beveled shape ofthe end part VXB of the via VX and also by the fact that the beam PTLmounted cantilever fashion, will inflect when the end zone ZXT comesinto contact with the beveled part VXB of the via VX, and allow, by thisraising, passage of the zone ZXT on the other side of the via.

Once the zone ZXT has passed the other side of the via (secondconfiguration) the via VX can descend again and hook the zone ZXT bybeing in contact with the latter.

And, in this second configuration, the beam PTR of the assembly ENS1cannot naturally return to its first configuration even if thetemperature returns to the initial temperature since the beam PTR islocked by the via VX.

In the second configuration, it therefore becomes possible to establishan electrical link passing through the body CPS and through the beamPTR.

Check mechanism MCTL, disposed for example in another part of theintegrated circuit, can thus test the establishment or otherwise of thiselectrical link.

In this regard, it will be possible to use any conventional and knownmeans. The mechanism MCTL can for example comprise a generator able togenerate a supply voltage on the edge BDA of the housing LG and verify,for example with the aid of logic circuits, that the current thusgenerated is indeed present at the level of the edge BDC of the housing,the edges BDA and BDC being electrically insulated.

Whereas in the embodiment illustrated in FIGS. 13 and 14, the switch CMTpossessed a naturally irreversible state, as explained hereinabove, itis possible, as illustrated in FIGS. 15, 16 and 17, to provide for theswitch furthermore to comprise a mechanism MLB configured to release abeam immobilized by the body CPS.

In the example illustrated in FIGS. 15 to 17, the mechanism MLB herecomprise, as illustrated in FIG. 16, a first arm BRS1 formed by a via,and a second arm BRS2 formed here by a metallic portion situated at themetal level N and by two vias disposed either side of this metallicportion.

The arms BRS1 and BRS2 are secured to the beam PTL in the vicinity ofthe end opposite from that to which the appendage VX is linked.

These arms BRS1 and BRS2 make it possible to immobilize the beam PTL andto permit simply as will be seen hereinafter, vertical sagging.

In addition to these arms BRS1 and BRS2, the mechanism MLB alsocomprise, as illustrated in FIG. 16, another beam PLB held fixed at itsright end, for example by way of a via. This beam PLB, produced at themetal level N, comprises in its left part a metallic, for examplealuminum, pointed element ELM having a structure analogous to that whichwas described with reference to FIG. 7 for example. It will be notedhere that the element ELM is ridded here of the subjacent support thatserved for its formation, as well as of the second material that servedfor the formation of the pointed regions. The pointed regions RGP aredirected towards the beam PTL of the body CPS.

The mechanism MLB also comprise a mechansim GENB able to generate apotential difference between the beam PTL and the beam PLB and thus tocreate at the level of the tips of the pointed element ELM anelectrostatic field so as to create a repulsion effect which will makeit possible to inflect the beam PTL upwards (motion MVT4). And, it isseen in FIG. 17 that on account of the sagging of the beam PTL, the beamPTR is freed from its immobilization constraints by the appendage VX andtherefore returns to its initial configuration (motion MVT3).

The switch CMT is then as it were reinitialized and can be used again tofor example detect the crossing of a temperature threshold or a surge.

The switch CMT and especially the assembly ENS1 as well as the body CPSare produced by carrying out conventional steps for fabricatingmetallization levels and vias. The levels of vias are also used to forma protection wall for the oxide etching which will allowde-encapsulation of the assembly ENS1 and of the body CPS.

Moreover, the beam PLB and especially the element ELM is produced in amanner analogous to what was described hereinabove with reference toFIGS. 1 to 7 by using for example as subjacent support silicon dioxideetched so as to form a pattern of salient blocks allowing the productionof the aluminum layer and its projections.

Reference is now made to FIGS. 18 and 19 to illustrate a use of apointed element in a system for detecting the spatial orientation and/orthe change of this orientation of an integrated circuit. An exemplarysystem for detecting orientation and/or change of orientation isdescribed in French patent application No. FR1252988.

Certain characteristics thereof are recalled here.

Referring to FIG. 18, it is seen that the system DIS for detectingspatial orientation and/or the change of orientation of the integratedcircuit CI is produced within several metallization levels (here threemetallization levels M_(i−1), M_(i), M_(i+1) and two levels of viasV_(i−1), V_(i)) of the interconnection part RITX (BEOL) of theintegrated circuit CI. The metal is for example aluminum.

The system DIS comprises a housing or cavity CV whose walls comprisemetallic portions produced within various metallization levels.

In the present case, the system DIS comprises a floor wall PLCH producedat the metallization level M_(i−1), a ceiling wall PLFD produced at themetallization level M_(i+1) and a lateral wall PLT comprising metallicportions produced at the metallization level M_(i) and vias produced atthe levels of vias V_(i−1) and V_(i).

The system DIS also comprises a metallic piece 1 housed in the housingCV and mobile inside this housing.

The system DIS also comprises a check mechanism, for example pillarsPLR, defining inside the housing an evolution zone ZV for the metallicpiece and comprising less two electrically conducting elements, forexample the pillars PLR, disposed at the boundary of the evolution zone.

The metallic piece 1 is configured so as, under the action of gravity,to come into contact with the pillars PLR in response to at least onegiven spatial orientation of the integrated circuit.

The integrated circuit also comprises detection mechanism MDT configuredto detect an electrical link passing through the piece and theelectrically conducting elements PLR.

This mechanism MDT is, in the example described, connected to thepillars PLR by a connection CNX which can be produced in various ways,for example by way of vias and of metallic tracks at different levels ofthe integrated circuit.

Moreover, in certain cases, it may be necessary to electrically insulatethe pillars PLR from the bottom wall and floor wall PLCH and PLFD. Inthis case, an insulating space ESP is made around the metallic portionof the wall PLCH which supports a pillar PLR.

The mechanism MDT, supplied between a supply voltage Vdd and earth, areof conventional and known structure. It is possible in this regard touse any appropriate logic circuit.

The mechanism MDT has been represented in a schematic manner outside theintegrated circuit. This could actually be the case if this mechanismMDT is produced as a distinct component of the integrated circuit. Ofcourse, this mechanism MDT could also be integrated into the integratedcircuit CI.

Initially, the piece 1 is in this example a metallic portion of themetallization level Mi, encapsulated in an isolating region part. Afterremoval of this isolating region part, so as to form the cavity CV, thepiece 1 becomes mobile and, in the case illustrated in FIG. 18, falls bygravity onto the floor wall PLCH.

When the integrated circuit is in a horizontal position, as illustratedin FIG. 18, the piece 1 and the pillars PLR are mutually arranged insuch a way that the piece 1 does not come into contact with at least twopillars PLR. No electrical link is detected by the detection mechanismMDT. This is consequently representative of a flat integrated circuitCI.

On the other hand, if the integrated circuit CI is tilted, the piece 1will then under the action of gravity slide on the floor wall PLCH so asto contact at least two pillars PLR. An electrical link between thesetwo pillars PLR will be able to be detected by the mechanism MDT. As afunction of the location of the pillars PLR with which the piece 1 hascome into contact, it is then possible to detect that the integratedcircuit CI has taken a given orientation, or at the very least anorientation included in a given range of orientations.

So as to limit a risk of sticking of the piece 1 on the floor wall PLCHand consequently to favor the sliding of the piece 1 on this floor wall,it is particularly advantageous, as illustrated in FIG. 19, to providefor this floor wall PLCH to incorporate a pointed element ELM directingits pointed regions towards the metallic piece 1 inside the evolutionzone ZV. The element ELM is ridded of the subjacent support that servedfor its formation as well as of the second material that served for theformation of the pointed regions.

Here again the system DIS is produced with conventional steps forfabricating metallization levels and vias. The levels of vias are alsoused to form a protection wall for the oxide etching which will allowthe formation of the cavity CV.

Moreover, the element ELM of the floor PLCH is produced in a manneranalogous to what was described hereinabove with reference to FIGS. 1 to7 by using for example as subjacent support silicon dioxide etched so asto form a pattern of salient blocks allowing the production of thealuminum layer and its projections.

What is claimed is:
 1. A method for producing an integrated circuit pointed element, the method comprising: forming an element having a projection with a concave part directing its concavity towards the element, the element comprising a first etchable material; forming a zone around the concave part of the element, the zone comprising a second material that is less rapidly etchable than the first material for a particular etchant; and etching the first material and the second material with the particular etchant to form an open crater in the concave part and thus to form a pointed region of the element.
 2. The method according to claim 1, wherein forming the zone comprises forming a layer of the second material above and around the at least one concave part and removing a portion of the layer of the second material so as to abrade a crown of the concave part.
 3. The method according to claim 2, wherein forming the crater comprises simultaneously etching the first material and the second material.
 4. The method according to claim 3, further comprising removing the second material after the etching of the first material and of the second material.
 5. The method according to claim 1, wherein the element and the projection comprise the same first material.
 6. The method according to claim 5, wherein forming the element comprises forming a support comprising a block and performing a compliant deposition of a layer of the first material on the support, part of the layer overlapping the block forming the projection.
 7. The method according to claim 1, wherein forming the element comprises forming an element having a plurality of projections, wherein the first material and of the second material are etched so as to form an open crater in each concave part and thus to form several pointed regions.
 8. The method according to claim 7, wherein forming the element comprises forming a support comprising a plurality of blocks and performing a compliant deposition of a layer of the first material over the support, part of the layer overlapping the blocks forming the projections.
 9. A device, comprising an element of an integrated circuit having at least one projection, the element comprising a pointed region in an upper part and a base in a lower part, the pointed region limiting an open crater and broadening out from a pointed end towards the base.
 10. The device according to claim 9, wherein an external wall of the pointed region exhibits a concave profile extending from the opening of the crater and directing its concavity towards the crater.
 11. The device according to claim 9, wherein the crater exhibits a hollowed part at a foot of an internal wall of the pointed region.
 12. The device according to claim 9, further comprising a support possessing a block, wherein the element is located above the support.
 13. The device according to claim 12, wherein the pointed region is auto-aligned with the block.
 14. The device according to claim 9, wherein the projection and a remainder of the element comprise one and the same first material.
 15. The device according to claim 9, wherein the element comprises a plurality of projections, each projection having a pointed region.
 16. An integrated circuit, comprising: a support; and an element having a projection disposed over the support, the element comprising a pointed region in an upper part and a base in a lower part, the pointed region limiting an open crater and broadening out from a pointed end towards the base.
 17. The integrated circuit according to claim 16, wherein the integrated circuit comprises a capacitor that includes two electrodes separated by a dielectric layer, at least one of the electrodes being formed with the element.
 18. The integrated circuit according to claim 16, wherein the integrated circuit comprises an interconnection part comprising several metallization levels separated by an isolating region, the element being metallic and situated on one of the metallization levels.
 19. The integrated circuit according to claim 18, further comprising a mechanical system for electrical switching within the interconnection part, the mechanical system including the element.
 20. The integrated circuit according to claim 19, the mechanical system comprising a first deformable assembly in a housing, the first deformable assembly including a beam held in at least two different places by at least two arms secured to edges of the housing, the beam and the arms being metallic and situated within one and the same metallization level, the mechanical system further including an electrically conducting body.
 21. The integrated circuit according to claim 20, wherein the first deformable assembly has a first configuration when it has a first temperature and a second configuration when at least one of the arms has a second temperature different from the first temperature.
 22. The integrated circuit according to claim 21, wherein the beam is remote from the body in the first configuration and in contact with the body and immobilized by the body in the second configuration so as to be able to establish or prohibit an electrical link passing through the body and through the beam, wherein the first deformable assembly is activatable to pass from one of the configurations to another.
 23. The integrated circuit according to claim 22, wherein the mechanical system further comprises a release mechanism configured to release a beam immobilized by the body and comprising the element, the pointed region being directed towards the body.
 24. The integrated circuit according to claim 23, wherein the mechanical system further comprises a generator configured to generate an electrostatic field at a level of the pointed region.
 25. The integrated circuit according to claim 18, further comprising a mechanical system for detecting spatial orientation and/or change of orientation of the integrated circuit, the mechanical system disposed within the interconnection part and comprising the element and a housing whose walls comprise metallic portions produced within various metallization levels.
 26. The integrated circuit according to claim 25, wherein the housing comprises a floor wall and a ceiling wall and wherein the mechanical system includes a metallic piece housed in the housing and mobile inside the housing, a check mechanism with the housing providing an evolution zone for the metallic piece and comprising at least two electrically conducting elements disposed at a boundary of the evolution zone.
 27. The integrated circuit according to claim 26, wherein the floor or ceiling walls incorporate the element and direct the pointed region towards the metallic piece inside the evolution zone, the piece being configured so as, under the action of gravity, to come into contact with the electrically conducting elements in response to a given spatial orientation of the integrated circuit.
 28. The integrated circuit according to claim 27, further comprising a detector configured to detect an electrical link passing through the piece and the electrically conducting elements. 